Can I confirm knife action with mouse, or other key than Enter?
This is mapped by default to Enter, NumpadEnter and Space but you can change it if you want to.



To change it, you go to User Preferences > Input.


In the search field, type Knife and it will bring up the relevant panels
Toggle Knife Topology Tool
Toggle, Knife Tool Modal Map
Change any of the Confirm options to whatever input you want by clicking in the input field to the right and then pressing the key you want to use OR
* You can add another one with Add new at the bottom.